1. Technical Field
The invention relates to air springs and, in particular, to air springs having an internal bumper which acts as a back-up in case of air spring failure or to absorb sudden large deflections or shocks imparted on the air springs. More particularly, the invention relates to a bumper extension for use on an air spring having an already-existing bumper utilized in the air spring, where the bumper extensions are positioned over the existing bumper in either a single or a stacked configuration so as to allow the adjustment of the stop height of an air spring without requiring the replacement of the existing bumper.
2. Background Information
Pneumatic springs, commonly referred to as air springs, have been used for motor vehicles and various machines and other equipment for a number of years to provide cushioning between movable parts, primarily, to absorb shock loads imparted thereon. The air spring usually consists of a flexible rubber sleeve which extends between a pair of end members which contain a supply of compressed air and may have one or more pistons located within the flexible sleeve. The end members mount the air spring on spaced components or parts of the vehicle or equipment on which the air spring is mounted.
The internal pressurized fluid, which is generally air, absorbs most of the shock impressed upon or experienced by one of the spaced end members by which the air spring is mounted, with the ends members moving axially toward and away from each other upon absorbing the imparted shock. Examples of such air springs are well known in the art and include U.S. Pat. Nos. 4,787,606, 4,852,861, 4,946,144 and 5,201,500.
Certain of these prior art springs have internal bumpers mounted on one of the end members which extends into the interior of the pressurized chamber. The bumper prevents total collapse or deflection of the spring member in the event of air spring failure. The bumper also absorbs shock upon the spring experiencing severe shocks and deflections which result in actual or near "bottoming out" of the spring member. Heretofore, these bumpers consisted of an elastomeric member which was mounted on a stud extending outwardly from one of the end members, such as is shown in U.S. Pat. Nos. 4,787,606 and 5,201,500. Although these elastomeric bumpers are satisfactory for most applications, it is found that several disadvantages or inconveniences result from their use, including the requirement of lubrication, special equipment to assemble the bumpers on the projecting studs, and the inability to alter the height of the bumper without complete removal and replacement thereof.
Therefore, the need exists for an improved type of air spring bumper which eliminates the heretofore-used elastomeric bumpers, thereby overcoming any disadvantages of their use.
Examples of other prior art inventions including shock-absorbing components are set forth in the following summaries.
U.S. Pat. No. 3,658,314 discloses a fluid shock absorber having an elastomeric member mounted between two concentrically movable tubes with an elastomeric bumper mounted beneath the inner tube to absorb impact from the tube.
U.S. Pat. No. 4,218,599 discloses a polymer spring for use in a drawer of a cabinet to ensure that when the drawer is closed, it does not rebound to a partially open position.
U.S. Pat. No. 4,342,264 shows another type of air spring using an elastomeric bumper mounted on one of the end members.
U.S. Pat. No. 4,478,396 discloses an elastomeric bumper which is mounted on the top of a vehicle strut.
U.S. Pat. No. 4,506,910 discloses a bumper 60 mounted on the inner surface of mounting plate 53 of the air spring, whereby the bumper provides a limit to any extreme swinging of the beam attached to the piston opposed to the mounting plate.
U.S. Pat. No. 4,787,606 shows a rubber bumper attached to the inner surface of one of the end plates by a pin where the rubber bumper serves to prevent total collapse or deflection of the spring assembly.
U.S. Pat. No. 4,925,224 discloses an energy-absorbing bumper with an elastomeric bumper module. The energy-absorbing bumper is attachable to a vehicle where it serves to absorb the energy of an impact of that vehicle with another object.
U.S. Pat. No. 5,201,500 shows an air spring in which a post is mounted on one of the end members and extends into the fluid chamber where a shock-absorbing bumper is formed and snap-fitted on the enlarged top of the post.
However, no known prior art, including those discussed above, disclose an air spring having an internal bumper that receives bumper extensions to provide height adjustability of the bumper.